BLOOD-PLATELETS EXPRESS HIGH-LEVELS OF THE PP60C-SRC-SPECIFIC TYROSINE KINASE-ACTIVITY
BLOOD-PLATELETS EXPRESS HIGH-LEVELS OF THE PP60C-SRC-SPECIFIC TYROSINE KINASE-ACTIVITY
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DOI：
10.1073/pnas.83.4.852
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发表时间：
1986-02-01
影响因子：
11.1
通讯作者：
BRUGGE, JS
中科院分区：
文献类型：
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作者：
GOLDEN, A;NEMETH, SP;BRUGGE, JS
我们已经研究了人和兔血小板表达pp 60 c-src，Rous肉瘤病毒转化蛋白的正常细胞同源物。通过使用烯醇化酶作为底物的免疫复合物激酶测定法测定pp 60 c-src激酶活性，通过免疫印迹测定法测定pp 60 c-src蛋白水平。与其他组织中发现的水平相比，血小板裂解物表达高水平的pp 60 c-src特异性激酶活性和pp 60 c-src蛋白。还发现pp 60 c-src是从血小板分离的膜中体外磷酸化的主要蛋白质之一。在膜磷酸化反应中，除了pp 60 c-src之外的多种蛋白质种类也在酪氨酸上被磷酸化，并且磷酸酪氨酸代表80%的总磷酸氨基酸残基在膜中磷酸化。这些结果表明，酪氨酸激酶代表的主要蛋白磷酸化酶检测分离的血小板膜。尽管酪氨酸激酶活性与许多病毒癌基因产物和细胞生长激素受体的相关性表明这些酶在调节细胞增殖中发挥作用，但这些结果表明高水平酪氨酸激酶活性的表达并不完全与细胞增殖有关。
We have examined human and rabbit blood platelets for expression of pp60c-src, the normal cellular homolog of the transforming protein of Rous sarcoma virus. pp60c-src kinase activity was determined by an immune-complex kinase assay that uses enolase as the substrate, and pp60c-src protein levels were determined by an immunoblot assay. Lysates from platelets expressed high levels of pp60c-src-specific kinase activity and pp60c-src protein compared to the levels found in other tissues. pp60c-src was also found to be one of the major proteins phosphorylated in vitro in membranes isolated from platelets. Multiple protein species other than pp60c-src were also phosphorylated on tyrosine in the membrane phosphorylation reactions, and phosphotyrosine represented .apprxeq. 80% of the total phosphoamino acid residues phosphorylated in the membranes. These results indicate that tyrosine kinases represent the major protein phosphorylating enzymes detected in isolated platelet membranes. Although the association of tyrosine kinase activity with many viral oncogene products and cellular growth hormone receptors has suggested a role for these enzymes in the regulation of cell proliferation, these results indicate that the expression of high levels of tyrosine kinase activity is not exclusively associated with proliferating cells.